首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1578187篇
  免费   29630篇
  国内免费   7123篇
电工技术   35069篇
综合类   6627篇
化学工业   280062篇
金属工艺   66219篇
机械仪表   46544篇
建筑科学   47682篇
矿业工程   11516篇
能源动力   51966篇
轻工业   119917篇
水利工程   15666篇
石油天然气   37700篇
武器工业   192篇
无线电   202948篇
一般工业技术   297936篇
冶金工业   185571篇
原子能技术   34528篇
自动化技术   174797篇
  2021年   16819篇
  2020年   12773篇
  2019年   15618篇
  2018年   17827篇
  2017年   17186篇
  2016年   23192篇
  2015年   18460篇
  2014年   30433篇
  2013年   90321篇
  2012年   38999篇
  2011年   52690篇
  2010年   45587篇
  2009年   53520篇
  2008年   48028篇
  2007年   44704篇
  2006年   46805篇
  2005年   41313篇
  2004年   43071篇
  2003年   42988篇
  2002年   41741篇
  2001年   38906篇
  2000年   37110篇
  1999年   36621篇
  1998年   52709篇
  1997年   43610篇
  1996年   38255篇
  1995年   32572篇
  1994年   30378篇
  1993年   30118篇
  1992年   26683篇
  1991年   23929篇
  1990年   24103篇
  1989年   23148篇
  1988年   21698篇
  1987年   19935篇
  1986年   19382篇
  1985年   22570篇
  1984年   22591篇
  1983年   20544篇
  1982年   19445篇
  1981年   19563篇
  1980年   18169篇
  1979年   18690篇
  1978年   17896篇
  1977年   17926篇
  1976年   19474篇
  1975年   16122篇
  1974年   15650篇
  1973年   15717篇
  1972年   13144篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
The effect of microwave roasting parameters (300, 450 and 600 W; 5, 10 and 15 min) on acrylamide content in sorghum grain was determined using High Pressure Liquid Chromatography (HPLC)-photo diode array (PDA) detector coupled with C-18 column. Samples roasted at 300 and 450 W did not possess acrylamide, whereas 600 W (15 min) favoured formation of 2740.19 µg/kg of acrylamide, levels far exceeding the defined European Union (EU) limits. The chronic daily intake (CDI) for acrylamide through consumption of such grain flour was 3.25–9.5-fold higher to Joint FAO/WHO Expert Committee on Food Additives (JECFA) defined high exposure limits. The margin of exposure (MOE) values ranged from 4.3 to 12.76 and from 11.07 to 32.27 for neoplastic and neurological effects, respectively, demonstrating high exposure and serious health concerns associated with dietary intake of this toxicant. This study assesses the risk for the Indian population and highlights the importance of optimising process parameters for food product to minimise such exposure risks.  相似文献   
22.
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized...  相似文献   
23.
Theoretical Foundations of Chemical Engineering - On the basis of the classic concepts of the theory of solid-phase combustion, for the first time, a model with a detailed scheme of chemical...  相似文献   
24.
25.
Multimedia Tools and Applications - Recently, many concepts in technology has been changed. According to the digital transformation trends, Internet of Things (IoT) represents an interested...  相似文献   
26.
In this study, dilute chemical bath deposition technique has been used to deposit CdZnS thin films on soda-lime glass substrates. The structural, morphological, optoelectronic properties of as-grown films have been investigated as a function of different Zn2+ precursor concentrations. The X-ray diffractogram of CdS thin-film reveals a peak corresponding to (002) plane with wurtzite structure, and the peak shift has been observed with the increase of the Zn2+ concentration upon formation of CdZnS thin film. From morphological studies, it has been revealed that the diluted chemical bath deposition technique provides homogeneous distribution of film on the substrate even at a lower concentration of Zn2+. Optical characterization has shown that the transparency of the film is influenced by Zn2+ concentration and when the Zn2+ concentration is varied from 0 M to 0.0256 M, bandgap values of resulting films range from 2.42 eV to 3.90 eV while. Furthermore, electrical properties have shown that with increasing zinc concentration the resistivity of the film increases. Finally, numerical simulation validates and suggests that CdZnS buffer layer with composition of 0.0032 M Zn2+ concentration would be a promising candidate in CIGS solar cell.  相似文献   
27.
Combustion, Explosion, and Shock Waves - Results of a numerical study of mixing, ignition, and combustion of a cold hydrogen jet propagating along the lower wall of a channel parallel to a...  相似文献   
28.
Multimedia Tools and Applications - In this work, a new fuzzy logic-based algorithm is proposed for the enhancement of low light color images. A generalization of a fuzzy set known as an...  相似文献   
29.
Multimedia Tools and Applications - The three-dimensional models of brain tumors serve as diagnostic assistance for physicians, surgeons, and radiologists. The proposed system establishes an...  相似文献   
30.

We discuss the temperature dependence of a common low temperature local thermometer, a tunnel junction between a superconductor and a normal metal (NIS junction). Towards the lowest temperatures its characteristics tend to saturate, which is usually attributed to selfheating effects. In this technical note, we reanalyze this saturation and show that the temperature independent subgap current of the junction alone explains in some cases the low temperature behavior quantitatively.

  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号